Buggy code:
; private static final String [ ] L_R_N_M_B_H_F_V_W_SPACE = new String [ ] { "L" , "R" , "N" , "M" , "B" , "H" , "F" , "V" , "W" , "<seq2seq4repair_space>" } ; private static final String [ ] ES_EP_EB_EL_EY_IB_IL_IN_IE_EI_ER = new String [ ] { "ES" , "EP" , "EB" , "EL" , "EY" , "IB" , "IL" , "IN" , "IE" , "EI" , "ER" } ; private static final String [ ] L_T_K_S_N_M_B_Z = new String [ ] { "L" , "T" , "K" , "S" , "N" , "M" , "B" , "Z" } ; protected int maxCodeLen = 4 ; public DoubleMetaphone ( ) { } public String doubleMetaphone ( String value ) { } public String doubleMetaphone ( String value , boolean alternate ) { } public Object encode ( Object obj ) throws EncoderException { } public String encode ( String value ) { } public boolean isDoubleMetaphoneEqual ( String value1 , String value2 ) { } public boolean isDoubleMetaphoneEqual ( String value1 , String value2 , boolean alternate ) { } public int getMaxCodeLen ( ) { } public void setMaxCodeLen ( int maxCodeLen ) { } private int handleAEIOUY ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleC ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleCC ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleCH ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleD ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleG ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index , boolean slavoGermanic ) { } private int handleGH ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleH ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleJ ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index , boolean slavoGermanic ) { } private int handleL ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleP ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleR ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index , boolean slavoGermanic ) { } private int handleS ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index , boolean slavoGermanic ) { } private int handleSC ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleT ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleW ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleX ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index ) { } private int handleZ ( String value , DoubleMetaphone . DoubleMetaphoneResult result , int index , boolean slavoGermanic ) { } private boolean conditionC0 ( String value , int index ) { } private boolean conditionCH0 ( String value , int index ) { } private boolean conditionCH1 ( String value , int index ) { } private boolean conditionL0 ( String value , int index ) { } private boolean conditionM0 ( String value , int index ) { } private boolean isSlavoGermanic ( String value ) { } private boolean isVowel ( char ch ) { } private boolean isSilentStart ( String value ) { } private String cleanInput ( String input ) { if ( input == null ) { return null ; } input = input . trim ( ) ; if ( ( input . length ( ) ) == 0 ) { return null ; } <START_BUG> return input . toUpperCase ( ) ; <END_BUG> } protected char charAt ( String value , int index ) { } private static boolean contains ( String value , int start , int length , String criteria ) { } private static boolean contains ( String value , int start , int length , String criteria1 , String criteria2 ) { } private static boolean contains ( String value , int start , int length , String criteria1 , String criteria2 , String criteria3 ) { } private static boolean contains ( String value , int start , int length , String criteria1 , String criteria2 , String criteria3 , String criteria4 ) { } private static boolean contains ( String value , int start , int length , String criteria1 , String criteria2 , String criteria3 , String criteria4 , String criteria5 ) { } private static boolean contains ( String value , int start , int length , String criteria1 , String criteria2 , String criteria3 , String criteria4 , String criteria5 , String criteria6 ) { } protected static boolean contains ( String value , int start , int length , String [ ] criteria ) { } public class DoubleMetaphoneResult { private StringBuffer primary = new StringBuffer ( getMaxCodeLen ( ) ) ; private StringBuffer alternate = new StringBuffer ( getMaxCodeLen ( ) ) ; private int maxLength ; public DoubleMetaphoneResult ( int maxLength ) { } public void append ( char value ) { } public void append ( char primary , char alternate ) { } public void appendPrimary ( char value ) { } public void appendAlternate ( char value ) { } public void append ( String value ) { } public void append ( String primary , String alternate ) { } public void appendPrimary ( String value ) { } public void appendAlternate ( String value ) { } public String getPrimary ( ) { } public String getAlternate ( ) { } public boolean isComplete ( ) { }

Fix:
return input . toUpperCase ( Locale . ENGLISH ) ;